A really, really strange Excel problem

[MartinLiss]

Create this sub, put a breakpoint on the End Sub line and execute it

Sub test()
Dim strCol As String
strCol = "AJ"
'MsgBox strCol
End Sub

In my Excel if I check at the breakpoint what strCol is, it shows up as blank! However if I uncomment the MsgBox line the Msgbox shows AJ.

Note that if I change strCol to "XX" or any other value (as far as I know), strCol becomes XX with or without the MsgBox.